Pneumatic spring



A. P. BOURNE.

PNEUMA'HC SPRING.

APPLICATION FILED JULY 16, 191s.

1,373,71 l Patented Apr. l5, 1921.

2 SHEETS-SHEET I.

A. P. BOURNE.

PNEUMATIC SPRING.

APFLlcAnoN man )um/16,1918.

1,373,71 1 l Patented Apr. 5, 1921.

aca/aderjawv@ NUnir-sn STATES PATENT orifice.

ALEXANDER P. BOURNE, ory BARRINGTON, RHODE ISLAND.

PNEUMATIC SPRING.

To all wlw/m, t may] concern Be it known that I, ALEXANDER. Bouman, a citizen of the United States, residing at Barrington, in the county of Bris- .i-,tol-and State ot" Rhode Island, have invented certain new and useful Improve-V ments in Pneumatic Springs7 of l.which the following is a specification.

This invention relates' tor improvements 1.10,; in pneumatic springs. More particularly it relates to springs in whiclifan expansible chamber, preferably made of two tubes that telescope together, and by havingA closed outer ends contain air or other compressible liluid; althoughV more or less of the chamber contents may be an incompressible Huid, such as oil, without altering the essentiallyT pneumatic characteroi' the spring. The in'- vention relates especially to that type of 2,0:2 apparatus in which an everted, highly Hex# ible sleeve joins the teleseoping Vmembers and constitutes a. septum' that prevents' leak! age at the joint between the tubes. Such springs may be nearly frictionless' in operan 26,5 tion. When applied to 'a'veliicle,`t he gaseous Huid medium-wliicli suoli a spring introduces between the roadand the load, practically eliminates the lesser vibrations which ordinarily are felt by passengers, makes the 30.11 maj or vibrations less objectionable, and permits them to be reduced with lessshoclr.

The invention comprises an improvement in apparatus of this character several respects7 one of"'ivliicli Vis that it provides means by which the load :carrying ability or stiffness of`tlie springflis automatically changed when 'a change occurs in the load which the vehicle on an individual spring is carrying, so that the car body tends to iofoccupy la predetermined normal elevation abovethe aXle, with the normal range of 4resiliency and oscillation up and down there-` decreaseof the load carried, does have such an eilect. `Another feature is the device by `which the two elements of the spring arey i centered with their axes coinciding, and are specification of Letters raient.

Application filed July 1G, 1918. Serial 110,245,230.

Patented Apr. 5, 1,921.

caused to oscillatein and out with a maxi-y mum of rectilinear precision and with a minimum of friction, at the same time'preventing abrasion offthe relatively delicate septum which holds theiluid medium.` Anl? 60? other feature provides for reducing the am-` plitude of those movements which are oscillatory, as distinguishedy from more perma# nent shiftings resulting from actual change of load, and doing tliisgently and 'by the 651 automatic action of tlies'pring. Other'ifeatures of the'invention relate to thev details of constructingtlie chamber andthe septum and its connections, 'ior tight holding and quiclrremovability to take the 'spring apart 70y or to repair it, and to the details of mounting the spring on a vehicle; and tothe general problemof applying the principles of the invention in a mannerthat is commercially practicable asl regards expense and 775 adaptability to "current practice in' vehicle construction, and 'as' regards simplicity and reliability, and in other respects developing the utility of the invention. Itis also the y object of the inventionto provide the vother 8'0 advantages that are incidental to"th,e disi`-` closure herein made. The invention may be embodied in various forms. [It is intended thatthe patent shall cover7 byjsuit'able eX- pression in the appended claims, whatever features of patentable novelty exist ,in the inventionherein 'disclosedf f rin embodiment of `the .invention is illus trated in the accompanying`clraivings, in., which- 'f 90` Figure l is an elevation in sectionon the" line ll of Fig. 2, portions being slightly out of the medial plane, and represented as if rotated into the medial plane vof the dey, vice; y f y Fig. `3 is an elevation of a detail in section. on the line 3 3 of Fig., 2, showing theidevice nwhich is illustratedv for attaching the spring toa vehicle body; i. l

Fig. 4l is an elevation, insectionontlie .same plane as Fig. 3, but showingA details at the other end of the spring,v`wherel it is attached tothe aXle; y"

Fig. 5 is aside elevation ofa portion of 105 vthe parts shown in Fig. 4, showing a ldetail of the. attachment to theaxle, and

Fig. 6 is a sid velevationof` a modifica-i tion.

it' wiii 'be unciersiooa" that nl "pistes ai@ 110 drawing is diagrammatic, and that any approved or suitable construction may be substituted for that indicated.

Referring tov the drawings, the two' ele-'i' ments between which the spring extends are marked respectivelyV 10 and 2O the former being illustrated as a support firmly securedv on a heavy rod 11 which may be assumed to be a diagrammatic representationof a suitably strong non-rotating part of the rear axle of aniautomobile; and the latter being a supportk which,'as 'indicatedin Fig. 3, may besupposed. to representv the vehicle body, frame, Vorother part which is supported by the spring', the :sameibein'g indicated at 21,v

Figs-2 and 3. The main Velements of the spring are .the plunger member 12and the incasmgmember 22.*which are adapted to telescope together, and the highlyV flexible sleeve septum13 which prevents leakage of their contents. Vlhisseptum,fwhich may be made of `any suitable material, has the gen` eral characteristics that it is cylindrical and open-ended. One end'is adapted to fit and be fast to the outside of the plungerat its inner end, whence the septumextends outward a 'distance along on the external wall of the plunger to a continuously varying place, where it is everted,` bridges the'spa'ce be tween plunger and casing, and thence tends inward along'the interior wall of the casing to the remote end thereof, where the other endof the septum is fastened. One feature of the invention relates to the arrangement and fastening of this septum so that it and its related parts can be cheaply7 gravity tends to draw away any foreign matter. The plunger 12 is a simple piece of metallic .tubing whose lower end screws down' intoV an underlying base cap 14 herein termed the base of the spring. `This base is supported on a nub 15 rising from a sub base 16 whichris secured tothe fundamental supporting element 10 of the spring. A The engagement between the base 14 and the -nub of the sub-base is merely a socket in which b v its expansive tendency'the spring presses the Vbase 14 outward into engagement with the nub. rlhe latter is set in so deeply that the Aparts cannot be separated, and cannot move materially sidewise while they are;f

together, without the spring being collapsed;

septum is made.

the drawing marked' 12 and constitutes anV the other.

but when the pressure' within the spring is sufliciently reduced the base may be lifted freely from the.sub.base. Similarly, at the top there is a cap hereincalled the top of the spring 24 and a super-top 26, the top having a nub 25 which fits into a depression on the under side of the super-top 26, wherein it is held ordinarily by the expansible power of the spring, but from which it may be moved when the spring is sufficiently weakened andjcollapsed. lSide -rods 26 afford a connection, at times, between the super-top 26 and ears 14" on the base 14. Similarly, side rods 24 afford a connection at times between the top 24 and ears 16V Vprojecting from thesub-basel. Thefunction and operation of these parts will be explained hereinafteri Thelower end of the plunger is closed by the base 14,'and the upper end'of the casing is closed by the'top 24.` The expansible chamber 2Bis between these two; and asl the upper endA of the plunger. is 'Y open,` within the casing, the chamber includes the interior space of both.

`rl`he invention'provides an important means for attaching one end of the septum to the open upper end of theplunger; This con sists in lieveling the said end as a section of Y a cone and having its material thick enough to make this surface long enough to support the corresponding concave section of a cone in which the-inner surface of the end of the The line referred to is in air-'tight closure. The septum itself may conveniently'be composite, of textile fabric and rubber. A layer of the fabric may supporta layer of the rubber, and should be of sufliciently line texture to 'prevent therubber from being blown 4through its kintersticeswhen under high pressure. This texf tile fabric-should alsobe capableof such lateral expansion and contraction as will permit .it to lie smoothly either on the external lcylindrical surface ofthe plunger 12 orion the materially larger interior cylindri cal surface of the casing 22, Preferably this is enough larger to permit of there being an easy bend of the septum around from one to The smaller theradius of curvature of this bend the greater the pressure of kcontents whichr the apparatus can hold without rupture. The septum may be relatively thin, in order to yattain highV fiexibility; and if` high flexibility be attained,1coupled with narrowness of space betweenthe two adja,

VThe end of this septum is prepared to be seated on the endof theplungeratthe line o 12. lby being thickened into a triangular :or wedge shaped cross ,section'asillustrated Having .beenput into place, the Aflanged retaining ring 13 may be dropped over it and will hold itv securely. This is a simplecylindrical ring with its body portion, large enough and long enough .to surroundY the diameter of the plunger plus septum, so that ity will compress the septum alittle, especially just belowits head. When the ,appa-w ratus is in action, the fluid pressure within the inclosed spacegor chamber constituted by the casing and plunger, which in closure or chamber is referred. to lby the reference numeral 23, forces the septum outward at its fold between'thevplunger and the casing, c

and tends to draw the Vwedge head thereof 13 closely upon they beveled end of the plunger 12 and tightlyiagainst the inside of 1, .theretainin g ring 13 so that no air can pass.

The joint may be made moresecure against leakage bykapplying a sticky liquid which evaporates but little, and preferably is soluble in water sothat it can bequicklywashed" away. An example is dark grade molasses which does not (crystallize orfhardenV on exposure, but remains sticky.A Antileak liquids,

common for pneumatic tires, will also provide so that no air can escape at this place, A similarly constructed fastening for the septum is provided at its other end.l In consequence the construction of this part of the apparatus is one of extremesimplicity. The

plunger is a simple tube' with screw at one end and bevel at the other; the retaining ring is a simple flanged ring; the septum is a cylindrical sleeve of suitablematerial with thickened ends, whichfmay bevulcanized; and the casing is a simple tube with screw f thread at one end. So long as the plunger moves 1n ,and out with its axis toinciding` with that of the'casing, the septum will roll from one metal surface to the other, practicallyV without friction. 1 Y

To guide the casing and plunger with their axes thus coinciding, a device is provided which consists of anfinternal plunger, fast to the casing 22 and marked 27, which is smaller than the plunger 1.2 and projects down into it, moving in and out as the..

spring contracts and expands, and centered therein by a series of rolling balls, 17, which,

held inY a ballvcarrier 17 with lubricatingv feltr17, 4substantially fill the distance between it andthe inside of the main plunger' l2, there being only" such clearance as is de sirable for jfree action. This carrier has four horizontal rows of four or more balls each, staggered, so that each ball has a f n Y p rods will hold the main parts `,of the spring.

separate track, although for clearness in Fig. 1 upper and lower balls are shown as if y they were arranged to travel in the same f track. :This carrier is maintained ina l,cer-

tain`` Vpredetermined normal middle position by two springs marked respectively 1,7 and 27 which incasethe plunger 27, the former from the lower edgeof theballn extendin carrier 1, tothebase 14 and the latter from the upper ed'gelof'ithelball carrier to lthe top l 24.f These springs, beingof such.. strength and design thatthey come to a balance `with the ball carrier` and its balls at lthe middle...

position, and. yield.E and expand equally as thespring collapses or expands. This prof vides a substantially frictionlesscentering bottom caps, thesprings 1,7,and 2r .'SO device. y As the rolling cfa ball on the main in balance 'with the balls between them at this position.

Hence the springs and the .l

rolling action of theapparatus cooperate to hold the ball carrier and ballsin the middle r position where they will be mosteilicientin preventingfbending of the inainapparatus.

As ball carriers may extend:` for av Vcon-v siderable distance in the axial direction, this centralffloating brace,or bending preventive,`can bemade A'very stronggand may give abundant/,rigidity to the telescoping meinbers." If thegcompression lis ever. suiliciently violent,"a pad :14 restingonthe base 1 4` at the bottom `ofthe chamber 23. receives the flange 24.- onthe lower-end of the auxiliary plunger.-27. vTheiatter plunger, therefore,

l should be strong enough, and suiiicientlyfse-f curedl to-the top. 24, to; withstand such a .1.

Y stress. It ydoesy no'harnif'the upper and lower row of balls run off of the edgeswhen the spring is most fullyv extended, for two rows of balls remain to guide the parts ac* curately together upon thenext contractionI of theV spring; and also 4because gbya device f hereinafter to-be explained an extreme `expansion ofthe distance `between the super-` top and the sub-base, inthe particularaprparatus illustratech'is accompaiiiediby and retarded by contraction of.y the distance between top and base,.the supertop separating from the top,.andthefsub-base from the baise, for that purpose.' As the .and .the`

' superftop become engaged together for this l purpose, throughrods 26.', and onfurther' spread vthesub-base and the top become en- ,f

gagedthrouglithe rods 24f",the nub is made vlong enough to `keep theL base :and sub-base on the same axis during such a separation until all is held secure by the engaging of the sub-base and the top.` Thecentering nubs 15` and-25 are maderounding to assure the cen- .f

tering of thespring uponthereturn to nori the projectionsof the supertop around the:

Y the ysame'relative position, which obviously approximately in place in case of deflation or accidental side pressure.

Air maybe admitted to the chamber 23 through an inlet pipe 30 whichv as represented may be considered to be' the terminal fragment of a system of flexible piping'outside of the spring and leading to the spring from a` reservoir (not shown) which main-T tains a supply of air under pressure. Such air may pass in from the pipe 30V through the pipe 3l and through a check valve indicated diagrammatically at 32, arrangedso that the failure of'pressure in the reservoir pipe-30 closesit; and through another hav.

ing a stem 33 whichy projects into the cham-l ber 23 within the internal plunger 27, arranged in position'to be' engaged by a device therein and pushed outward ,with sufficient force to overcomethis pressure. These may be valves of any ordinary orsuitable auto- ,maticl style, preferably of the puppet valve v type, set 1n a passage through a 'removable screw plug filling a hole through cap 24 as indicated.` Thus the valves can be quickly" examined or replaced. Air may escape from the chamber 23 through an 4outlet which is provided with avalve having a stem 34 which projects into the chamber within the internal plunger 27. This valve is indicated" diagrammatically at 35, is similarly a puppet valve located in a'removable plug, andV merely discharges intothe Voutside air. lIt is closedl by the pressures which normally prevail within' chamber 23, which are considerably above Vatmos1: heric, but`is opened a when aY device within the chamber pullsY its stemf34 withv sufficient force. For that purpose its stem has ay lug 35, represented as a4 lnut with check nut;V Within the internal plunger a regulatingv device has Aan annular lug 36, adapted to engage and operate either the outlet'valve stem 34 or the inlet valve stem 33 when needed to restore the normal condi tions for which the regulator is set. `These conditions may be,`for example, a requirel mentthat the top andthe baseA shall .maintain an average distance from each other about lilrethat portrayed in the drawing.

n In other words, assuming that the. spring is installed under a vehiclewhich isV at rest, the spring should automatically put, its various parts into substantially the vposition indi-V cated, If the spring be compressed as by they addition of a passenger, or by addition of several tons of` load, therspring should presently automatically restore its parts to stantially the relative position `of parts illusQ trated. The regulator must not; interfere with the free play ofthe spring, extending and contracting to the full extent desirable in performing its function as a'spring; and

extensions vor contractions whichv are constantly resulting from roughness of the'road V'70 in consequence 'the momentary and repeated j must not cause more air to be admitted or airto be discharged.` .The rfeatures ofthe" invention which relatel to this will now be'4 described.

The varying positions of the lug"36are determined by an averaging device having a'retarded action. This, 'represented as auf ranged symmetrically on Vthe main axis, consists of a closed cylindrical' cup 40 adapted to Vcontain liquid41, suchas oil or glycerin..

. The cup 4() is carriedon a piston 42iwhose piston rod 43 depends rigidly from the top cap V24. The cup is: easily movable upfand Y down along the mainaxis of the apparatus, as itis from time to time propelled by the preponderating"influence vof either the!E spring 44 which pushesit'upward ortne spring V45wliich pushesitdownward, submakes the apparatus inthe natureof .a dash'- pot. The piston rod 43 holds the pistonf42 at a fixed position with respect toY said "top l,

cap. The bos's4( limits the extent to which ject to the retarding eifectofthe liquid 41 l and piston 42 which'has an opening 4G thatH theV cup can approach the top.; and a spacing` sleeve 48 strung on the piston rod andiresting on the piston limits the rextent to which it can'move Vaway from Ythe to'p cap,ea chj limit being somewhat beond thedistance which the cup, t e annular lug 36,

Y must move, either upward to open the valve 33, v32V for admittingair, or downward to open'the valve 34, 35 for letting out air. If

preferred, the parts 42, 43and 48 mayall be of one xpiece. The'springl45 Visvlocated within the lower partof thecup, extends from thepiston 42,` whichV for this purpose isthe equivalenti ofthe top cap l24, tothe bottom of the cup '40,andtends Aalways to f push the cup downward', which would move its lug 36 in the direction Vfor llettingout air,

and so decreasing pressure. The spring 44V ,which extends from'thebase cap 14, to an `external flange 44"suitably located on the cup, tends always tov push the cup and its l lug 36 upward, in the Vdirection for lettingin air and so increasing ,the strength of the spring. The parts may be designed and set so that when the pressure of air within is right to maintain the spring as a whole v.dis-

tended to the desired normal degree, under whatever load it is carrying at thetime and with the. cup 40 then at rest, `the lug 36 is between its valve engaging positions, engaging neither. This assumes that the springs 1 44 and 45 are balancing each other, with no tendency of the suspended cup 40 to move tent.

either upward or downward.` The 'flange 44 is made movable and has a lock nut. 'By this means the normal position of the regulating cup and the normal distance between the top and the base, and the axle and the load may be varied.

The operation of this part of the appara tus will be understood by supposing that the spring is set in place in a vehicle and thus at rest, and that a'load is then added. The addition `of the load compresses the whole spring, bringing the top 24 and bottom 14 nearer together. `This puts the springs 44, 45 out of balance,for owing to the piston and liquid the Acup 40` does not immediately change its position with respect to the top 24, and so the'springv 44 is compressed more than spring Y 45; The former therefore tends to move the cup and its lug` 36 upward, to restore, the balance, moving slowly as the liquid Vpasses through the opening in the piston. 1When the lug 36 thus moves far enough to engage the valve stem 33, and pushes it hard enough to lift it, air begins to flow from anoutside 'high pressure supply through the pipe30 into the interior space 23 of the chamber. `The admission of' this air tends to restore 'the whole spring to its former degree of ex- 30:

pansion; and the expanding movement tends to move and gradually `does move the cup 40 and lug36 downward, z'. e., away from the top cap 24, because the top 24 and the bottom 14 are separatingfarther from each otherwithout-the springs 44, 45, expanding immediatelyto a corresponding ex- The delay is due, ,of course, to the dash-pot, but as the rexpansion makes spring 44 relatively and momentarily weaker than spring 45, in its eiiect on the cup, the cup and lug 36 begin to move away from the top cap 24 underjtheunbalanced influence of spring 45, and, when they have moved far enough, cease to be in contact with the valve stem 33, so that the "admission of air ceases. lf then a portion of the load lbe removed the spring asa whole tends to expand, with the result that the top cap 24 and the base cup 14 move farther apart. As the spring 44 expands, the opposition which it has been affording to its counter spring 45 is reduced, with the' result that spring 45 expands, pushing the cap 40 and its lug 36 to a greater distance from the top cap 24 until said lug engages the valve stem 34 and opens the air discharge valve. `The discharge valve remains open until the air pressure within has become so much reduced that the spring as a whole has contracted 'under the existing load to a spread in which the spring 44 so nearly balances spring 45 that with the aid of the air pressure within the chamber 23 that valve is able to close, and to litt the lug 36 as much as is needed to acn complish that. In. 'all ordinary cases the retical than actual, because of the livecharacter of the load, or because of quickly repeated and varyingV shocks sustained in passing over a road, and even from the oscillation of the spring V.itself resulting when a load is changed; This problem is somewhat difficult because'the apparatuslacks humanV intelligence to know whether a vcontraction, for example, is due to addition of loador to striking an elevation inthe road; and if the'latter whether it will continue permanently, like an up grade, or is merely a stone in the road. The vsolution consists in making a distinctionbetween permanent and temporary conditions and in providing so that the valves will not be opened by mere contraction or 7expansion of the spring, b'ut only when such expansion or` contraction lasts for a suliicient interval 4of time to be inconsistent with a temporary cause. If oscillation of the spring is occasioned by the sustaining of a compressive shock, an oscil-V latory expansion immediately follows which neutralizes the eiect `of the initial oscillatory contraction; and these in turn arek followed by successive n, and alternate compressions and expansions. Ulf these balance each other, and if neither alone is su'liicient to move the lug 36 enoughto open a valve, the spring as a whole performs its Vfunction as a normal spring without altering its stiffness. But, if the initial compression benot followed by an expansiornfor kiithe oscillations ensue about ay different center` orzero point, the lug 36 willA tend tofbef moved so as to correspond in positionwith thel new center of oscillation.` The function" of the dash-pot, consisting of the piston 42 within the cup with provision4 for retarded flowif of a liquid from one side of it to the other, is to prevent either valve 32 or 35, from being operated by mere oscillation of the spring. The dashpot should be designed to t have a su'llicient slowing 'actionto prevent one oscillation of the main spring from moving the cup 40 on` its` piston enough to open either valve.A Assuming that the apparatus is in a normal position, with the lug 36 midway between itslvalve 'engaging positions,the balancing, or the averaging, as it were, of the oscillations, by each one more or less undoing the elfect of the preceding one, produces a net" re,sult which, acting throughthe period ,of time required bythe dasl1-pots retarding effect, registers the average or permanent condition and 1at `the same time automatically proceeds to correct izo it, it correction be needed. v"And this occurs,

ratus has to dowith the side rods 24 anc 26" and their coiinections, which are respectively V such that when the spring is extended far QenOugh, the top' 24 `becomes' engaged with `the sub-base 16, and the base 141 becomes fengaged withthe super-top 26. The spring as thusfardescribed is `so perfectly resilient Vowing .tothe almost entire absence of fric- .tion that its ,oscillations might extend far- 1.0 t I tion, which is thus automatically established between top and'A bottom when a certain degree of extension has been had, provides an elastic stop for furthereXpansion of the ther than is desirable and require to be checked by a .lug strap as is usual with springs under an automobile. The connecspring, in that. after the spring has reached the limitof extension afforded by the setting of rods 241- and 26 further separation of fthe axle and vehicle. body can be Vaccomplished only. compressing the spring,

which thus Vbrings that oscillation gently to an end v. If desired, buffer springs or pads .24 and 26 may be interposed to' eliminate noise .when the engagement is thus made.V As illustrated, the rods V26 become engaged with `lugs 111 iirst lbefore rods 24 .engage lugs 16. r1`he expansion of the spring is Vthus stopped', and vduring the vinterval until lugs 16 become engaged the 'rweight of the vehicleand load `alone are resistiiig the 11p-throw. If this is not su'liicient, the engagement of lugs 16 `,which ensues adds the weightyof the running gear., through the .main spring which intervenes and is compressed until the upwardvmovement ceases.. Thusl the' upward throw by oscillation ofthe spring is gently restrained byfirst cutting off the spring drive and by .next employing the spring to resist the drive momentum and togive a positive rewarding 40 l nary automobile .construction with anl air action. VThis makes it possible-to serve ordispring considerably shorter than the telescoping principle of the main' parts 12. and 22 would otherwise require. This shortening makes such springsk more conveniently adaptable for specific constructions'to which springsof this type have not heretofore been readily applicable. The distance and dimensions that would otherwise have to be provided for oscillation of the spring :in4 the direction of expansion are largelysaved.

. While the spring or biiifer herein described may .beused in connection with vari- .ous kinds of apparatus and may be connect- Ved thereto in numerous ways, the present drawing illustrates'a device which l have found useful' for connections when it is applied as amain spring under a vehicle, with the important advantages that it provides a full proportion of the'available surface of a spherical bearing for Y sustaining vertical.

stresses; and that economizes vertical space, which is limited under the body of Aan automobile.V In such-a case, it is desir- Vable to provide a connection which permits "for the other. vene between the studs and the spring and .spring is attached are studs hav-ing spherical heads; and their bearings consist of the two parts 10 and 16 for one, and 20 and 26 The parts 16 and 26 inter- Y are in-factV respectively thel sub-base and vsuper-top, herein fpreviously mentioned.

The spherical head of the Studis held against the part 16 or 26 by the yoke member 10 or 20, which maybe rigidly screwed to 'the sub-base or super-top as indicated; and each .pair is so shaped interiorly that it fits far enough around the .spherical headyto hold it; and. not far enough to prevent the necessary amount of universal play. Y By merely removing the bolts, 10,.20 the apparatus can be taken from the vehicle. f Or, without opening the bearing as that would do, the

apparatus can be taken'from the vehicle by `merely pulling out the elements 10, 20,1after unscrewing their retaining nuts.

Although the device for automatic control .of the pressurewithin, consistingof the cup .40 andkassociated parts, and valves 32,'and l375, are illustrated as being arranged centrally in the interior of the apparatus, which f is a preferred arrangementhaving a number of advantages, Vit is not necessary that they be within it. They-,may be outside, The

important feature in this respect is that the controller should be sensitive to the eXpan- `sive and contractive movements of the apparatus, as by Abeing connected between the top and bottom thereof, andthat it should, asitresponds, reach deviceswhich open or close the appropriate valves; Nor is it necessary' that the engagement of this controller with the valvesbe byfdirect, or by `solely mechanical, means as here illustrated; for a direct Vconnection and the use of means other than mechanical vfor actuating valves.

,whetherV those valves be set within the capl as illustrated or be conveniently locatedoutside:thereof, may be preferred under some circumstances. One utility of the inside arrangement which'is illustrated is that danger A of leakage incidental to the device for making the connection between the Controller and the valves is eliminated, and .that the `only risk of leakage is such as is inherent vin the .valves themselves. And 'of that `,ber of individual springs are used4 together danger the apparatus is automatically cor- `rective, ff'or if pressure Iwithin grows too high, owing to leakage of inlet valve 32 the spring will become expanded and correction will be madeby the opening of the valve 85; and the reverse is true in'case of leakage ofthe latter valve. As the airthus iiowing isautoinatically` replaced,fand can be suppliedfrom a reservoir lwith vair at higher pressure carried at a convenient place on the vehicle, which `may* be charged by a simple power-driven air pump, which latter maybe one of some suitable and known automatic type,.the entire system may be automatic in the sense that it maintains proper resiliency or stiffness for each spring, "as predetermined, regardless of changes'of load or of unevenness of load or of road.

In the case of vehicles, s uch astrucks, which "A20 are subject to wideranges ofA loadingthis is a matter of considerable importance as affecting their speed of operation over the road, and the wear of parts, and other operative details. Arrangement of lthe controller outside'may be desirable when a numin' a lgang to `act as one unit, as under a rail- Yway car. f lThenone controllerimay'worka single inlet valve, for nthe whole' unit, and a single discharge, the chambers 23 Vof all vthe individuals being connected by a" continu- The general operation lof the apparatus is that theV plunger 12 and -casing`22 telescope in and out practically -without friction land with the perfect resiliency that is charfactei'istic of'a perfect gas.' The only oppor- Ltunity for friction isA in therolling of theA balls 17, whose friction iis negligible because they merely intervene between two` `oppositely moving surfaces and rotate practically n situ, and in the bending of the septum at Aits moving fold 13, which requires no more power `than the bendingof a small and'flexible piece Vof cloth, lf desired there may be-two valves 35, and two -valves v32, 'each pair being symmetrically arranged soV as to prevent any binding of the cup 40 on the pistony and rod `To Atake the apparatus apart for renewing a septum or for other attention Ito the interior, removal" of the side rods and the screws 24 that hold together the two parts of thejcap 24 permits removal ofthe outside part of thedatter, and the casing 22.

The upperfend of the septum 13, Ibe'ingl flexible, can be slipped over the conical inner partof the top cap24, because of the neck of less diameter just below it; and said lcap an'd the interior plunger with contents are thus exposed 'orremoved 'For'setting the apparatus, the ',annul'arflugT 36 be screwed up or downen the cup 40to the desiredY position' with respect tolthe #two valves which it operates preferably, however, the adjustment is 'accomplished vby screwing the nut 44 up andfdowii on the cup 440 to vary the place where springs44 and45 balance each other; The plug'conitaining the valves 32, 33 and-'the plug containing the 4valve 35 caii be removed by `unscrewing. from the cap 24." The lug `35 fof' the latter is gotten past 4they lug 36 by tipping the plug sidewis'e as it isftaken,` out,-

said plug being Vmade of two diameters, the inner and` smaller ofwhich has a screw thread engagement with the cap short yenough sothat when backed out it becomes l clear of the screw threa'dfbefore the lug 35 engages ther lug at the topmost position ofthe latter, and-with' room enough for these two to pass each othery when tipped. The "position oflug 35 on its valve stem 'caiithen be adjusted.` `However, openings may be provided through the cylinder 27, if desired, for access to the nutllfugl 35 and to thejnutsY 44 and'so that these canv bey adjusted withoutextensive removal 'of-parts. l`Ordinarily' these valves t33,? 35 will be so designed and the lug 36-s'o set that there `will1be' somei'vhat` of `a spaoejwithin which Athe lug 36 can gfiuctuatein ordinary puse, Vwithout opening i either valvelf A lseptum `of, the nature"4 described will last fora long time; but if'through any cause* `it is injured or gives out' it can be" quickly removed by the method described. The :process of 24 can beset aroundit,v without disturbing the relative adjustment of the parts.

The septum is made in any suitable way; preferably 'it has oney or'fmore layers of flexiblefabri'c, of 4cotton or the like, supporting a sheet rubberlayer, ,the threads of `the fabricr being soarranged that the cotton 'fabric is expansilble circumferentiallyand 'can lie; smoothly either on the` exterior of the plunger 12 or fon' `"thelarger surfaceof the; interior of thecasiiig 22 and so that the threads do not separate'enough to allow the interiorhcoating of rubber 5to bulge'through betweenany of them. 'The'preferred jweave is withjtight' 4threadso'ne way and loose the othenp.Althoughthe septuinfis spoken of as being ofa generallyfcylindrical shape, its ends may be preferablyaformed. and vul- .canizedfinthe size which `they are *tov have lwhen in use;` and if: this be done the inner end is somewhat smallertthanthe outerend, corresponding to thesmaller 4diameter of the plungerwhich itfitsr, i

i vwThe inventionis/illustrated asitmay be applied tofsa'ch'amber whichfis wliolly'con- 4*1250 l Partly as a means of showing more clearly the principle of the arrangement,illustrated stituted within the plunger and casing l2,

:through the cap 24 with aconiined. space `outside of thepartsillustrated, as has-heretofore been proposed .in some cases; and such other confined spacemight either be of fixed dimensions, or might be one or more expansible chambers. f

in Fig..-l, a'modification is illustrated in F ig.,6, in which the various parts-are given the same reference numerals as elsewhere, but are arranged in a diiierentvrelation to each other, the rods 24 and 26v being all in the same plane, with the latter arranged farther from the axis so as to permitv this, Ainstead of being all equidistant from the axis but indifferent planes as illustrated in Figs.land2.- '7,

I claim as my'invention: y 1.` An 'air spring having normally closed inlet and outlet for air, and means actuated by expansion of the spring to openthe outlet, and-by contraction to open the inlet; anda device intervening between said means and the moving parts of the spring,V actuating said meansand itself: being actuated withthe spring actuationsand'composed of means transmitting the` impulses with less fresilience than air.

2. An air spring,combined with' means to maintain -a predetermined normal degree of expansion .thereof under differing loads, said spring having yinlet and outlet valves for "air,

both ofwhich are normally closedat said normal degree of expansion", means'to actuate them; operatedby the mutualapproac'h or recession ofthe elementsholding the air;

and a retarding device less resilient than air,

V.interveningbetween said elements and'V said jactuating means, ,and delaying the 'transmis sionrof' the motion of saidelementsto the to the main moving membersof the spring adapted automatically toopen said inlet, or said outlet, for maintaining a predetermined normal degree of expansion ofthe spring; said additional means including a liquid and a resilient solid and being adapted to respond tochange of mean degree 'of expansion of the spring as distinguished from responding 'to the elastic oscillations thereof. 4. An air springhaving inlet and outlet for air, combined'with afcontroller therefor, anda device setting thev controller according to the mean degree of the expansion vof the spring at 4the time being, as determined by the current oscillations thereof, including-a liquid dashpotand a resilient 'connection between the liquid and the main moving members of the spring, whereby its action on the 'inlet and outlet is approximately independent of said oscillations. v

5. An air spring having inlet and outlet for air, and a controller therefor actuated byfy expansion and contraction ofthe spring, combined with means causing the movement 4of said controller to lagsomuch behind the actuating movement of the spring as to feel the oscillation of the spring yin both direc-1 tions of its vibration before becoming eifecl tive to change the air inlet or outlet; the

Aconnection between said controller andthe moving parts of the spring being through a resilient solid. Y f f Y 6. An air spring, having inlet and outlet `for air through one wall of the spring, and

means mounted on said wall andmovable with relation thereto, by expansion and con- Y Ait in opposite directions, and extending VtoA it from opposite walls, with a resultant force tending to-move it yto lthatdistance-from the wall on which it is mounted where thesaid springs shall balance each other. Y

8. An air spring, having inlet and outle for air vthrough one wal-l ofthe spring, and means mounted on sai'dfwall and movable with relation thereto, by expansion and contractionof the spring, to control Vsaid inlet and outlet; its lsaid dash pot. Y Y c 9. An air spring, havinginlet andoutlet mounting including a Ifor airr through one wall of the spring, and

means mounted on said wall and movable 'with relation thereto, by expansion andl contraction of lthespring, to' control said inlet and outlet; its said mounting including' a cylindricalcup containing a liquid and a piston, the "said piston being immersed in the liquid within and supporting the cup, and

having a leak for the liquid past itself,

.whereby Vthe operating movement of the said 'controlling means with respect to-said wall is delayed yieldingly.

10. 'An air spring, having inlet and outlet for air through one'wall of the spring, and means mounted on said wall and movable with relation thereto, by expansion and contraction of the spring, to control said inlet and outlet; its said mounting including a `cup inside of which is a` spring tending to push the cup away from saidwall, and outside "of which is a spring engaged with the opposite wall and tending to push Vthe cup toward the rst mentioned Wall, whereby the position of said means with respect to the wall on which it is mounted depends upon the balance' between the said springs engaging it.

11,. An air spring, having inlet and outlet for air through oneA wall of the spring, and

means :mounted on said wall and movable with relation thereto, by expansion and contraction of the spring, to control said inlet and outlet.; its said mounting including a piston projecting from said wall, a cup mounted thereon, and a spring within the cup between said piston and its bottom tending to push it from said wall; and another spring engaging the other wall ofthe air spring, tending to push the said cup toward theliirst mentioned wall; and4 means adapted to delay the movement of said controller with respect to the 'wall on which it is mounted, when said opposing springs are out of balance.

12. An air spring, having inlet and outlet for air through one wall of the spring, and means mounted on said wall and movable with relation thereto, by expansion and contraction of the spring, to control said inlet and outlet; said mounting including a cup having Within it a spring tending to push the cup away from said wall and having without it a spring engaged with the opposite wall and tending to push the cup toward the first mentioned wall, whereby the position of said means with respect to the wall on which it is mounted depends upon the balance between the springs engaging it, there being a part on the cup adjustable in the direction of the action of said springs which engage it' whereby the position of the cup with` respect to the wall when said springs arein balance may be altered.

i3. An air spring, having inlet and outlet for air through one wall of the spring; puppet valves therefor, arranged to be automatically closedy by air pressure; and means mounted on said'wall and movable with relation thereto by expansion and contraction ci' thespring, havinga lug adapted to open the inlet valve when so moved by contraction, `and to open the outlet valve when so moved by expansion.

\ lll. An air Spring, having inlet and outlet for air through one wall of the spring; puppetvalves therefor, arranged to be automatically closed by Vair pressure; and'means mounted von said wall and movable with relation'thereto by expansion and contraction ofV the spring, having a lugfadapted to open the inlet valve when so moved by contraction ;^and to open the outlet valve when somoved byexpansion; there being in the inlet passage, outside of the inlet valve, an oppositely-facing check valve, preventing escape of air from the spring.

yl5. An air Spring, having inlet and outlet valves for air through one wall of the spring, with stems projecting into the spring; a support projecting from said wall and a member movable `thereon by expansion and contraction of the spring, comprising an annular lug adapted to engagethe said projecting stems of valves. f Y

16. ian air spring, having inlet and outlet for air through one wall of the spring; puppet valves therefor, arranged to be automatically closed by air pressure; and means mounted on said wall and movable with relation thereto by expansion and contraction of the spring, having a lug adapted toopen the inlet valve when so moved by contraction, and to open the outlet valve when so moved by expansion; the outlet valve having a Vstem projecting into the spring with a screw nut movable on it constituting an adjustable lug to be engaged to open the valve.

17. `An air spring, having inlet and outlet :for air through one wall of the spring; puppet valves therefor, arrangedto be automatically closed by air pressure; and means mounted on said wall and movable with relationthereto by expansion and contraction of the spring, having a lug adapted to open the inlet valve when so moved by contrac tion, and to open the outlet valve when so moved by expansion; the said valves being set in passages through removable plugs in said wall.

18. An air spring comprising a chamber having a plunger and a casing with a flexible sleeve septum intervening, having its end portions flexible but inextensible rings, and fastened at one end to the plunger; there being a cap closing the casing at the other end of the septum, separable into two parts one ci which comprises a disk capable of passing through the flexible septum endring and the other of which surrounds the disk annularly, the septiunend being smaller than the adjacent part of the septum in diameter and embraced between said two parts ofthe cap.

19. An air spring `comprising a chamber having a plungervand a casing with a flexible sleeve septum intervening, having its end portions flexible but inext'ensible rings, and fastened at one end to the plunger; there being a cap closing the casing at the other end of the septum, separable into two parts one of which comprises a disk capable of passing through the flexible septum end-ring and the other of which surrounds the disk annularly, the casing end and septum end being embraced between said two parts.

20. An air spring comiirising a chamber having a plunger and a casing with a flexible sleeve septum intervening, havingl its end portions flexible butinextensible rings, and fastened at one end to the plunger; there being a cap closing the casing at the `other end of the septum, separable into two parts one of which comprises a disk capable of passing through the flexible septum end-ring and the other of which surrounds the disk annularly, the septum end being smaller than the adjacent part of the septum in diameter and embraced between lsaid two parts of the cap; there being a conical surface onV one of said parts and Von the septum, and one of the parts overlying' the other, and the septum, whereby' compression of the parts together in the direction of the axis compresses the end of the septum. Y

2l. An air spring comprising a chamber having a plunger and a casing with a flexible sleeve septum intervening, having its end portions flexible but inextensible rings, and fastened at one end to the plunger; there being a cap closing the casing at the other end of the septum, separable into two parts one of which comprises a disk capable of passing throughthe flexible septum endring vand the other of which surrounds the Vdisk annularly, the septum end being smaller than the adjacent part of the septum in diameter and embraced between said two parte of the cap on all sides except where it is continuous with the remainder of the sleeve, and being there closely supported by said casing.

22. An air spring comprising a chamber having a tubular plunger and a casing, with a flexible sleeve septum intervening and fastened' to both; Vthe said fastening to the plunger tube comprising an end portion of the septum having a conical inextensible face toward the plunger end, and a conical end of the plunger supporting it, arranged with the pressure of ail within the chamber forcing them together.

23. An air spring comprising a chamber having a tubular plunger and a casing, with a flexible sleeve septum intervening and fastened to both; the said fastening to the plunger tube comprising an end portion of the septum having a conical Vinextensible face toward the plunger end, and a conical end of the plunger supporting it, arranged with the pressure of air within the chamber forcing them together; with a non-'drying tacky liquidintervening at said conical surface.

24. An air spring comprising a cylindrical tubular plunger and casing with intervening sleeve septum, means closing the outer ends thereof, means to maintain axial alinement, comprising an open ended cylindrical member, rigidly projecting from the closed end ofl the casing into and engaging the inner end of the plunger, inlet and outlet means Vfor air, and means located `within th@ diameter of said rigid member for opening thev inlet by a contracting movement and for opening the outlet by an expansive movement.

25. vAn airl spring comprising a cylindrical tubular plunger and casing with intervening sleeve septum, means closing theY outer ends thereof, and means to maintain axial alinement, comprising an open-ended cylindrical member, rigidly projectin fromI the Vclosed end of the casing into an engaging Athe inner end of the plunger; therefbeing a plurality of rings of rolling bearings intervening. r Y

26. An air spring comprising a cylindrical tubular plunger and casing with intervening sleeve septum, means closing the outer ends thereof, means to maintain axialv alinement, comprising an open-.ended cylindrical member, rigidlyprojecting from'the closed end of the casing into and engaging the inner end of the plunger; there being intervening a cage comprising two concentric cylinders of sheet metal with a multiplicity of balls sustained4 loosely in fixed positions therein, engaging the interior of the plunger and the exterior of said rigid cylindrical member.

27. An air spring comprising a cylindrical tubular plunger'and casing with intervening sleeve septum, means closing the outer ends thereof, means to maintain axial alinement, comprising an open-ended cylindrical member, rigidly projecting from the closed end of the casing into and engaging' the inner end of the plunger; there being intervening a cage comprising two concentric cylinders of sheet metal with a multiplicity of balls sustained loosely Vin fixed positions therein, engaging the interior of the plunger and the exterior of said rigid cylindrical member; and having a porous material adapted to hold lubricant.

28. An air spring comprising a cylindrical tubular plunger and casing with intervening sleeve septum, means closing the outer ends thereof, meansto maintain axial alinement, comprising anfopen-ended cylindrical member, rigidly projecting from the closed end of the casing into and engaging the inner end of the plunger; an annular anti-friction device through which said engagement occurs; and equal springs intervening between said device and the opposite ends of the air spring, whereby said device is maintained in medial position between said opposite ends.

29. An air spring comprising a cylindrical tubular plunger and casing with intervening sleeve septum, means closing the outer ends thereof, means to maintain .axial aline ment, comprising an open-,ended cylindrical member, rigidly projecting from the closed end of the casing into and engaging thev innerV end of the plunger; an anti-friction element intervening, and -means Vmaintaining 'it equidistant from the ends of the air spring during contractions and expansions thereof. f f

30. An air spring comprising a cylindrical tubular plunger and casing with intervening sleeve septum, means closing the outer ends thereof, means to maintain axial alinement,

comprising an open-ended cylindrical member, rigidly projecting from the closed end of the casing into and engaging the inner end of the plunger; an anti-friction element intervening, and supporting springs therefor counterbalancing each other when it is in the middle between the ends.

3l. An air spring, comprising telescoping members, having its support at one end separable into outer and inner parts, the outer part of which constitutes attaching means for that end of the spring; and connecting means from the inner part to the other end of the spring, having lost motion during the normal working range of the spring and becoming engaged at the limit thereof, thereby permitting further separation of the said outer part from the other end of the spring without further expansion of the spring; there being on one of the separated parts a stub, and on the other a cup adapted to receive it, whereby the parts come back into registry together after separation.

32. An air spring comprising a cylindrical tubular plunger and casing with intervening sleeve septum, means closing the outer ends thereof, means to maintain axial alinement, comprising an open-ended cylindrical member, rigidly projecting from the closed end of the casing into and engaging the inner end of the plunger; and an intervening cage comprising two concentric cylinders of sheet metal with concave tongues stamped and bent at right angles to sustain balls and a multiplicity of balls sustained loosely by these concave portions, engaging the interior of the plunger and the exterior of said rigid cylindrical member; and a porous material between the metal sheets, adapted to hold lubricant.

33. An air spring, comprising cylinders, telescoping together, combined with a flexible and everted sleeve septum intervening between said telescoping members; and a multiplicity of rolling incompressible members constituting bearings holding the telescopino' members in coaxial relation.

34e. n air spring comprising a chamber having a plunger and a casing, with a flexible sleeve septum intervening and having its end portions fitting against larger portions of the plunger and casing respectively; the septum being circumferentially inherently extensible. in its body portion and ineXtensible in its end portions.

35. An air spring comprising a chamber having a plunger and a casing, with a iiexible sleeve septum intervening, and having its end portions litting against larger portions of the plunger and casing respectively; the septum being circumferentially in herently extensible in its body portion and inextensible but collapsible in its end portions.

36. An air spring comprising a chamber' having a plunger and a casing, with a flexible sleeve septum intervening, having its end portions with conical faces adapted to fit against and incase conical faces of the plunger and casing respectively; the said end portions being inherently ineXtensible to size larger than the said plunger and casing parts against which they it, and being arranged for the pressure of air within the spring to tend toward making the fit tight.

Signed at Barrington this twenty-fourth day of June, 1918.

ALEXANDER P. BOURNE. 

